CVE-2026-77470

8.3High

Published 15 Oct 2026 · NVD status: Deferred · AI triage by gemini-3.8-flash

8.3High

Attack vector: Network
Complexity: Low
Privileges needed: None
User interaction: None
Impact: High impact on integrity
Weakness: CWE-20, CWE-472, CWE-915

Impact

Unauthenticated attackers can underpay for goods and trigger auto-fulfillment by manipulating payment parameters. They only need network access to an instance with an enabled webshop and an affected non-PayPal Omnipay gateway.

Root cause

The checkout service merges an untrusted additional_data array on top of server-computed purchase parameters, allowing request parameters to overwrite critical fields like amount and currency.

Affected systems

Lychee prior to 7.7.1

CVSS v4.0 · CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Fix & remediation

Upgrade to Lychee 7.7.1 or later. If patching immediately is not possible, disable the webshop feature or avoid using non-PayPal Omnipay payment gateways.

shell

$ git pull && composer install --no-dev

AI-suggested. Run it in staging first and check it against the vendor advisory. Why?

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NVD description

Lychee is a free, open-source photo-management tool. Prior to 7.7.1, the Supporter or Pro webshop POST /api/v2/Shop/Checkout/Process flow accepts an unrestricted additional_data array and CheckoutService::preparePurchaseParameters() merges it after server-computed purchase parameters. Because later string keys overwrite earlier keys, an unauthenticated buyer can replace amount, currency, returnUrl, cancelUrl, or transactionId before CheckoutService::processPayment() passes the parameters to a non-PayPal Omnipay gateway. An attacker can therefore make a gateway accept a successful payment for an attacker-selected amount and obtain auto-fulfilled goods while underpaying the merchant. The issue requires an enabled webshop, a purchasable item, and an affected Omnipay gateway. This issue is fixed in version 7.7.1.

References

Source: nvd.nist.gov/vuln/detail/CVE-2026-77470